Solvent Regeneration Equipment

Abstract

To efficiently reproduce a solvent through distillation.SOLUTION: A solvent reproduction device is formed, interposing a partition wall 16, with: a distillation tank 14 which has heaters 23 therein, and to which used solvents Sx are introduced; and a collection tank 15 which has, at a bottom part, a high boiling point solvent collecting part 31 and a low boiling point solvent collecting part 32 for respectively collecting two kinds of solvents which have, a difference in boiling points thereof, out of the used solvents Sx. On a part of the partition wall 16, there is formed a flow-down plate part 16a that makes fluid flow down to one side, and defines the distillation tank 14 on the lower side and the collection tank 15 on the upper side. The high boiling point solvent collecting part 31 is formed adjacent to a lower side of the flow down plate part 16a, and a cooling coil 36 is provided on a position except for an upper side of the flow-down plate part 16a and the high boiling point solvent collecting part 31 on the upper part of the collection tank 15, and below the cooling coil, the low boiling point solvent collecting part 32 is provided. On a front stage of the flow-down plate part 16a on the collection tank 15, there is formed an introduction hole 34 into which a solvent to be reproduced, is introduced.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a solvent regeneration device for regenerating a solvent used in cleaning objects such as glass substrates, liquid crystal display panels, electronic components, optical components, precision components, and metal components. [Background technology]

[0002] The method of recovering used solvents by distillation is used. When the used solvent is a mixture of two solvents with different boiling points, distillation is also used for recovery.

[0003] Patent Document 1 listed below discloses a solvent separation apparatus that separates a fluorinated solvent and HCs from a mixed liquid containing a low-boiling fluorinated solvent and a high-boiling HC. This apparatus is equipped with a downflow plate that is heated to a temperature between the boiling points of the fluorinated solvent and the HCs and causes the mixed liquid to flow down, and an HC recovery tank is formed downstream of the downflow plate. A fluorinated solvent recovery tank is formed adjacent to the HC recovery tank but away from the downflow plate, and a cooling and liquefaction means is provided above the fluorinated solvent recovery tank to condense the solvent that evaporates due to the heat of the downflow plate as it flows down the downflow plate, i.e., the fluorinated solvent.

[0004] Incidentally, such a mixed liquid (used solvent) consisting of two types of solvents is generated, for example, when removing organic material adhering to a metal mask in a vapor deposition process for organic EL.

[0005] That is, the object to be cleaned, such as a metal mask, is first immersed in a hydrocarbon solvent (HC) and cleaned. In this cleaning, the solvent dissolves and removes organic materials. After this cleaning process is performed in multiple stages, the object is rinsed and dried with hydrofluoroether (HFE), a fluorine-based solvent with a lower boiling point than HC. HFE has a higher specific gravity than water and HC, and a lower surface tension than HC.

[0006] In the rinse and dry process, HC attached to the object is dissolved and removed, and HFE attached to the object is vaporized and dried. After this, the object is further dried under vacuum (reduced pressure) to completely vaporize the trace amounts of HFE on the object.

[0007] For this reason, the rinse solution used in the rinse and dry process, HFE (used solvent), contains HC, but the proportion of HFE is greater than the proportion of HC. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 8-168601 Summary of the Invention [Problem to be solved by the invention]

[0009] As mentioned above, the proportion of HFE in used solvent is higher than that of HC, so if there is only one route for vaporization by heating, the efficiency of regenerating the solvent is poor.

[0010] Therefore, the main object of the present invention is to efficiently regenerate the solvent. [Means for solving the problem]

[0011] The means for achieving this is a solvent regeneration device in which a distillation tank having an internal heater and into which used solvent is introduced, and a recovery tank having a high-boiling point solvent recovery section and a low-boiling point solvent recovery section at the bottom, which recover two types of solvents with different boiling points from the used solvent, are formed via a partition wall, and a downflow plate section is formed in part of the partition wall, which allows fluid to flow down in one direction, with the distillation tank on the bottom and the recovery tank on the top, and the high-boiling point solvent recovery section is formed adjacent to and below the downflow plate section, a condenser is provided at the top of the recovery tank at a position excluding above the downflow plate section and the high-boiling point solvent recovery section, the low-boiling point solvent recovery section is formed below the condenser, and an inlet for introducing the solvent to be regenerated is formed in the recovery tank upstream of the downflow plate section.

[0012] In this configuration, the used solvent introduced into the distillation tank is heated by a heater, and the low-boiling solvent is vaporized and then cooled to a liquid state. At the same time, the heated used solvent heats the downflow plate of the partition wall. This causes the solvent to be regenerated, introduced through the inlet of the recovery tank—i.e., the same solvent as the used solvent introduced into the distillation tank and the low-boiling solvent circulating through the solvent regeneration device—to vaporize on the downflow plate. The unvaporized high-boiling solvent is stored in the high-boiling solvent recovery section, while the vaporized low-boiling solvent is cooled and liquefied by the condenser and stored in the low-boiling solvent recovery section. [Effects of the Invention]

[0013] According to this invention, regeneration by distillation is carried out simultaneously in both the distillation tank and the recovery tank, so the regeneration process can be carried out efficiently. Moreover, since the heater for distillation is shared by both distillations, it is also energy efficient. [Brief explanation of the drawings]

[0014] [Figure 1] Schematic diagram of a solvent regeneration device. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the present invention will be described below with reference to the drawings.

[0016] 1 shows a schematic structure of the solvent regeneration unit 11. The solvent regeneration unit 11 is installed next to an appropriate cleaning unit (not shown), receives a used solvent Sx, which is a mixture of two solvents with different boiling points, separates the low-boiling solvent from the high-boiling solvent, and supplies the resulting solvent to the cleaning unit as a regenerated liquid S.

[0017] The solvent regeneration device 11 has a main body 12 and a water separation tank 13, and the main body 12 is provided with a distillation tank 14 and a recovery tank 15 which are integrally connected via a partition wall 16.

[0018] The distillation tank 14 is a tank into which the used solvent Sx is introduced, and has an inlet 21 through which the used solvent Sx flows in, and the lower part of the interior of the tank is a liquid phase space 22 for storing the solvent. A heater 23 is provided at the inner bottom of the distillation tank 14 to heat the solvent to a predetermined temperature.

[0019] The upper portion of the interior of distillation tank 14 is a vapor phase space 24, which is provided with a liquid receiver 24b around vapor passage 24a, and a cooling coil 25 serving as a condenser above liquid receiver 24b.

[0020] A distilled liquid reservoir 26 for storing the distilled liquid is provided adjacent to the liquid receiver 24b. The distilled liquid reservoir 26 has a first transfer path 27 as a bypass for transferring the stored distilled liquid to the water separation tank 13.

[0021] Of the wall portions constituting distillation tank 14, a part of partition wall 16 adjacent to recovery tank 15, i.e., a part of the part of partition wall 16 corresponding to liquid phase space 22, is formed with a downflow plate portion 16a for causing the fluid to flow down in one direction. Downflow plate portion 16a has distillation tank 14 on the lower side and recovery tank 15 on the upper side, and has an inclined structure as a whole. Vertically extending upright walls 16b, 16c are formed above and below downflow plate portion 16a.

[0022] The downflow plate portion 16a allows the liquid to flow slowly over time. In the illustrated example, the downflow plate portion 16a has a stepped cross section, but any other suitable configuration can be used for the downflow plate portion 16a, such as an inclined plate with a baffle plate on its upper surface.

[0023] The heater 23 provided at the bottom of the distillation tank 14 is also provided below the downflow plate portion 16a.

[0024] The recovery tank 15 is a tank that removes 100% of the high-boiling solvent from the used solvent Sx. The recovery tank 15 has a high-boiling solvent recovery section 31 that recovers high-boiling solvents and a low-boiling solvent recovery section 32 that recovers low-boiling solvents in the lower part of the tank, and has an upper space 33 in the upper part. This upper space 33 extends integrally above the downflow plate section 16a of the partition wall 16 and above the high-boiling solvent recovery section 31 and the low-boiling solvent recovery section 32.

[0025] An inlet 34 for introducing the solvent to be recycled is provided in front of the downflow plate section 16a in the upper space 33, and a baffle plate 35 is provided above the upstream end of the downflow plate section 16a to receive the liquid sprayed from the inlet 34 and drip it onto the upstream end of the downflow plate section 16a.

[0026] The high-boiling-point solvent recovery section 31 is formed adjacent to and below the downflow plate section 16a so that the fluid flowing through the downflow plate section 16a accumulates therein. That is, the high-boiling-point solvent recovery section 31 is formed on the boundary of the vertical wall 16c formed below the downflow plate section 16a.

[0027] The low boiling point solvent recovery section 32 is formed adjacent to the high boiling point solvent recovery section 31 and away from the downflow plate section 16a. In other words, a cooling coil 36 serving as a condenser is provided in the upper space 33 inside the tank excluding the area above the downflow plate section 16a and the high boiling point solvent recovery section 31, and the low boiling point solvent recovery section 32 is formed below this cooling coil 36.

[0028] The cooling coil 36 of the recovery tank 15 condenses the vapor evaporated on the downflow plate 16a, and therefore does not necessarily have to be located higher than the downflow plate 16a. On the other hand, the cooling coil 25 of the distillation tank 14 is located higher than the upper end of the downflow plate 16a, since the downflow plate 16a is in the liquid phase space 22.

[0029] An air vent passage 37 for venting the air inside is formed above the low boiling point solvent recovery section 32, and this air vent passage 37 is connected to a position in the gas phase space 24 of the distillation tank 14 near the cooling coil 25.

[0030] The low boiling point solvent recovery section 32 has a water drainage passage 38 for discharging the water W floating on the top layer, and a pipe 39 for separating the low boiling point solvent accumulated in the bottom layer from the water W and discharging it.

[0031] The distillation tank 14 and the recovery tank 15 are provided with cooling coils 25 and 36, respectively, and these cooling coils 25 and 36 are connected to the same refrigerator 17, and are configured so that a cooling liquid controlled to the same predetermined temperature flows through them.

[0032] A regeneration circulation path 41 is provided at the bottom of the distillation tank 14, which circulates the solvent to the inlet 34. The regeneration circulation path 41 is equipped with a circulation pump 42, and a waste liquid path 43, which discharges waste liquid, is branched between the circulation pump 42 and the inlet 34 and is equipped with a switching valve 44.

[0033] In addition, a liquid transfer line 45 is provided at the bottom of the high-boiling solvent recovery section 31 in the recovery tank 15, for transferring the high-boiling solvent in the high-boiling solvent recovery section 31 to the regeneration circulation line 41. Specifically, the liquid transfer line 45 is provided with a switching valve 46 and is connected between the circulation pump 42 in the regeneration circulation line 41 and the distillation tank 14.

[0034] The water separation tank 13 is a device that introduces a low boiling point solvent and separates water W. The water separation tank 13 is provided downstream of the low boiling point solvent recovery section 32, and is connected to the low boiling point solvent recovery section 32 via a second transfer path 51 that is connected to the pipe 39 of the low boiling point solvent recovery section 32.

[0035] The water separation tank 13 is divided into two sections by a hanging wall 52 and an upright wall 53 that overlap each other in the vertical direction with a gap between them, and a second transfer path 51 is connected to the upper part of the upstream space 54. A water drain path 55 for draining floating water W is connected to a portion of the upstream space 54 that corresponds to the liquid level. A downstream space 56 is a portion where only the low-boiling point solvent accumulates, and a supply path 57 extends from the bottom of the downstream space 56 to supply the separated low-boiling point solvent as regenerating liquid S. In the figure, 58 is a liquid feed pump that sends regenerating liquid S through supply path 57.

[0036] An air vent passage 59 for venting the air inside is formed at the upper part of the front-stage space 54 and the rear-stage space 56, and this air vent passage 59 is connected to a position in the gas phase space 24 of the distillation tank 14 near the cooling coil 25.

[0037] Level gauges (not shown) for detecting liquid levels are provided at necessary locations such as distillation tank 14, distillate reservoir 26, and high boiling point solvent recovery section 31, and are used for drive control.

[0038] The solvent recycling device 11 configured as described above recycles used solvent Sx, which is a mixture of two solvents with different boiling points, as follows: Here, we show an example of recycling the solvent exemplified in the Background Art section, that is, the solvent used for cleaning to remove organic materials adhering to a metal mask in the deposition process of an organic EL device.

[0039] Used solvent Sx contains a mixture of hydrofluoroether (HFE), a low-boiling solvent, and hydrocarbon cleaning solvent (HC), a high-boiling solvent. HFE has a higher specific gravity than water or HC, and a lower surface tension than HC. The boiling point of HFE is approximately 60°C, while the boiling point of HC exceeds 100°C. This used solvent Sx contains a mixture of HFE and HC in a ratio of approximately 6:4.

[0040] The used solvent Sx is introduced into the inlet 21 of the distillation tank 14 of the main body 12 and is stored up to a position above the height of the downflow plate 16a in the liquid phase space 22 inside the tank. The solvent in the distillation tank 14 is heated by a heater 23, and the temperature is set to a predetermined constant temperature that is higher than the boiling point of the HFE and lower than the boiling point of the HC, for example, a temperature 5°C to 10°C higher than the boiling point of the low-boiling-point solvent. This set temperature is strictly controlled.

[0041] When the solvent in the distillation tank 14 is heated, the low boiling point solvent in the solvent boils and vaporizes, and the downflow plate section 16a is heated by the vaporization temperature.

[0042] The low-boiling point solvent vaporized in distillation tank 14 is cooled by cooling coil 25 in vapor phase space 24 and liquefied, and is transferred from liquid receiver 24b to distilled liquid reservoir 26. The bottom of distilled liquid reservoir 26 is transferred to water separation tank 13 through first transfer path 27.

[0043] In this way, the low boiling point solvent is separated by distillation in the distillation tank 14, while the solvent in the distillation tank 14 is sent from the liquid transfer line 45 through the regeneration circulation line 41 to the recovery tank 15 where it is separated.

[0044] That is, the solvent ejected from the inlet 34 of the recovery tank 15 hits the baffle plate 35 and then flows down onto the flow-down plate section 16a. At this time, since the flow-down plate section 16a is heated to a temperature equal to or higher than the boiling point of the low-boiling-point solvent, the low-boiling-point solvent in the solvent evaporates and boils to vaporize.

[0045] The vaporized low boiling point solvent rises, is cooled by the cooling coil 36, is liquefied, and is stored in the low boiling point solvent recovery section 32. In the low boiling point solvent recovery section 32, the low boiling point solvent is separated from the water W due to its specific gravity and accumulates in the lower layer, while the water W floating on the upper layer is discharged via the water drainage path 38.

[0046] Of the solvent, high-boiling point solvents that do not evaporate or boil at the temperature of the downflow plate section 16a flow down over the downflow plate section 16a and are stored in the high-boiling point solvent recovery section 31. By appropriately setting the heating temperature of the heater 23 based on the boiling point of the solvent, 100% of the high-boiling point solvent is recovered.

[0047] The high boiling point solvent stored in the high boiling point solvent recovery section 31 is discharged from the liquid transfer line 45 via the regeneration circulation line 41 and the waste liquid line 43 by switching the switching valves 46 and 44 .

[0048] The low boiling point solvent stored in the low boiling point solvent recovery section 32 is discharged through the pipe 39 and transferred to the water separation tank 13 via the second transfer path 51.

[0049] The low boiling point solvent introduced through the second transfer path 51 is first stored in the upstream space 54 in the water separation tank 13 together with the low boiling point solvent introduced through the first transfer path 27, and is separated from the water W by specific gravity, and the upper layer water W is discharged through the water drain path 55.

[0050] On the other hand, the low boiling point solvent in the lower layer passes between the hanging wall 52 and the standing wall 53 and moves to the rear space 56, and is supplied as the regenerated liquid S to the cleaning device through the supply path 57.

[0051] In this way, the low-boiling point solvent in the used solvent Sx is regenerated via two routes, the first transfer path 27 and the second transfer path 51. In other words, regeneration by distillation is carried out simultaneously in both the distillation tank 14 and the recovery tank 15, so the regeneration process can be carried out efficiently. Moreover, the distillation tank 14 and the recovery tank 15 are organically connected, and the heater 23 for distillation is used in common for both distillations, so energy efficiency is also good.

[0052] Furthermore, the cooling coils 25, 36 for liquefying the solvent are also connected to the same refrigerator 17, which also improves efficiency in this respect, and further allows the solvent regenerating device 11 to be constructed compactly.

[0053] The solvent regeneration device 11, in which the distillation tank 14 and the recovery tank 15 are integrated, is configured so that the high-boiling point solvent that is not recovered in the distillation tank 14 is 100% recovered in the recovery tank 15, which not only provides good energy efficiency but also makes it easier to regenerate the solvent without waste.

[0054] Furthermore, the regeneration circulation path 41 is connected to a liquid transfer path 45 that receives the high boiling point solvent recovered in the high boiling point solvent recovery section 31, and a waste liquid path 43 that discards the high boiling point solvent sent via the liquid transfer path 45, which also makes it possible to make the device compact.

[0055] Furthermore, a water separation tank 13 for separating water W from the low boiling point solvent is provided downstream of the low boiling point solvent recovery section 32, and a first transfer line 27 is connected to this water separation tank 13 as a bypass for introducing the low boiling point solvent separated in the distillation tank 14. Therefore, the solvent regeneration device 11 can be configured more compactly than when two water separation tanks are provided.

[0056] The above configuration is one embodiment for carrying out the present invention, and the present invention is not limited to only the above configuration, and other configurations can also be adopted.

[0057] For example, the low boiling point solvent may be a fluorine-based cleaning agent.

[0058] The solvent introduced into the inlet 34 may be subjected to a distillation process. [Explanation of symbols]

[0059] 11...Solvent regeneration device 13…Water separation tank 14...Distillation tank 15...Collection tank 16...Bulkhead 16a...Drop plate part 17...Freezer 23...Heater 27...First transfer route 31...High boiling point solvent recovery section 32...Low boiling point solvent recovery section 34...Entrance 36...Cooling coil 41…Regeneration circulation path 43...Wastewater channel 45…Liquid feed path 51…Second transfer path Sx: used solvent S…Regeneration liquid

Claims

1. a distillation tank having a heater therein and into which a used solvent is introduced, and a recovery tank having a high-boiling point solvent recovery section and a low-boiling point solvent recovery section at the bottom, which recover two types of solvents having different boiling points from the used solvent, respectively, formed through a partition wall; A flow-down plate portion is formed in a part of the partition wall, allowing the fluid to flow down in one direction, with the distillation tank on the lower side and the recovery tank on the upper side, and The high boiling point solvent recovery section is formed below and adjacent to the downflow plate section, a condenser is provided at a position in the upper part of the recovery tank excluding above the downflow plate section and the high-boiling point solvent recovery section, the low boiling point solvent recovery section is formed below the condenser, An inlet for introducing a solvent to be regenerated is formed in the recovery tank upstream of the downflow plate portion. Solvent regeneration equipment.

2. a condenser provided in the distillation tank is provided at a position higher than the upper end of the downflow plate portion, The condenser of the distillation tank and the condenser of the recovery tank are connected to the same refrigerator. The solvent regeneration apparatus of claim 1.

3. a regeneration circulation path is provided for circulating the solvent in the distillation tank to the inlet; The regeneration circulation path is connected to a liquid transfer path for receiving the high boiling point solvent recovered in the high boiling point solvent recovery section, and a waste liquid path for disposing of the high boiling point solvent transferred through the liquid transfer path. The solvent regeneration device according to claim 1 or 2.

4. A water separation tank is provided downstream of the low boiling point solvent recovery section, and a low boiling point solvent having a lower boiling point is introduced therein to separate water. A bypass is provided between the distillation tank and the water separation tank to transfer the solvent distilled in the distillation tank to the water separation tank. The solvent regeneration device according to claim 1 or 2.

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